Climate Change Risks on Mediterranean River Ecosystems and Adaptation Measures (Spain)

The Mediterranean is one of the most vulnerable regions to climate change impacts. Climate change scenarios predict that water temperature will increase up to 2.2–2.9ºC by the end of the century in Mediterranean rivers. This will cause an impact on water quality (oxygen dissolved reduction), reduce the available habitat of cold-water fish species and affect macroinvertebrates. Risk assessment methodology develops indicators that integrate hazard, exposure and vulnerability. Risk maps are key tools to prioritize the areas in which adaptation measures should be implemented in order to improve the adaptive capacity of ecosystems. The risk of habitat loss and ecosystem damage is very high in Mediterranean rivers. For RCP8.5, the 80% of the waterbodies that currently have brown trout presence are in High Risk (HR) or Very High Risk (VHR) of disappearing in the long term future (2070–2100) and the 35% in the short term (2010–2040). It will affect the middle sections first and the headwaters of the rivers later. The 92% of the waterbodies are in HR-VHR of macroinvertebrate family’s affection (2070–2100) and dissolved oxygen may be reduced by 0.5–0.75 mgO2/l (2070–2100). The restoration of the riverside vegetation is the main adaptation measure. This reduces significantly the stream temperature. Other measures are the groundwater protection and cold-water discharge from the reservoirs.